CA1184476A - Chain saw braking system - Google Patents
Chain saw braking systemInfo
- Publication number
- CA1184476A CA1184476A CA000427836A CA427836A CA1184476A CA 1184476 A CA1184476 A CA 1184476A CA 000427836 A CA000427836 A CA 000427836A CA 427836 A CA427836 A CA 427836A CA 1184476 A CA1184476 A CA 1184476A
- Authority
- CA
- Canada
- Prior art keywords
- latch
- sensing
- cam
- sensing arm
- housing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D59/00—Self-acting brakes, e.g. coming into operation at a predetermined speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
- B27B17/00—Chain saws; Equipment therefor
- B27B17/08—Drives or gearings; Devices for swivelling or tilting the chain saw
- B27B17/083—Devices for arresting movement of the saw chain
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Sawing (AREA)
Abstract
ABSTRACT
A chain saw safety braking assembly includes a sensing arm pivotally mounted to the housing and having a protrusion. A portion of the sensing arm is located in front of the gripping handle and is arranged to move from a first position to a second position in response to being struck by an appendage of the operator. A flexible brake band is disposed around the peripheral surface of a brake drum, and includes a first end anchored to the housing and a second end coupled to the sensing arm protrusion, such that when the sensing arm moves from the first position to the second position the flexible brake band is moved from a position free of the brake drum to a frictional braking relationship with the brake drum. A latch is rotatably mounted to the housing and is adapted to releasably engage the protrusion on the sensing arm. A spring anchored to the housing cooperates with the latch such that the latch yieldably holds the sensing arm in either the first or the second position. Thus when the sensing arm is struck, it will move from the first position to the second position stopping the chain movement. Additionally, an acceleration sensing assembly may be incorporated to sense acceleration of the saw, again typically due to kickback, and stop the chain should the acceleration rise above a preset level.
A chain saw safety braking assembly includes a sensing arm pivotally mounted to the housing and having a protrusion. A portion of the sensing arm is located in front of the gripping handle and is arranged to move from a first position to a second position in response to being struck by an appendage of the operator. A flexible brake band is disposed around the peripheral surface of a brake drum, and includes a first end anchored to the housing and a second end coupled to the sensing arm protrusion, such that when the sensing arm moves from the first position to the second position the flexible brake band is moved from a position free of the brake drum to a frictional braking relationship with the brake drum. A latch is rotatably mounted to the housing and is adapted to releasably engage the protrusion on the sensing arm. A spring anchored to the housing cooperates with the latch such that the latch yieldably holds the sensing arm in either the first or the second position. Thus when the sensing arm is struck, it will move from the first position to the second position stopping the chain movement. Additionally, an acceleration sensing assembly may be incorporated to sense acceleration of the saw, again typically due to kickback, and stop the chain should the acceleration rise above a preset level.
Description
CHAIN SAW BR~KI~G SYSTEM
The invention relates to the field of chain saws and particularly to a cutting chain braking system.
~ anually portable chain saws typically comprise an engine-carrying housing, a cutter bar projecting forwardly from the housing, and an engine-driven cutting chain entrained for endless mo~ement around the cutter bar. The chain saw is designed to be utili~ed by an operator grasping the machine with both hands. One hand of the operator normally holds a gripping handle mounted on the housing, while the other hand engages a housing control hanclle for actuating a trigger throttle mechanism.
In some instances of cutting operation, the cutting cha;n may encounter resistance of a type causing the cutter bar to kick upwardly in a manner commonly referred to as "kickback".
Generally the main method for dealing with this ! "kickback" phenomenon has been to incorporate a chain brake which can be actuated at the onset of "kickback", stopping the chain by means of the brake before contact with the operator.
Most chain saws incorporate a centrifugal clutch between the engine and the chain drive sprocket. A
typical clutch design is illustrated in U.S. Patent No.
The invention relates to the field of chain saws and particularly to a cutting chain braking system.
~ anually portable chain saws typically comprise an engine-carrying housing, a cutter bar projecting forwardly from the housing, and an engine-driven cutting chain entrained for endless mo~ement around the cutter bar. The chain saw is designed to be utili~ed by an operator grasping the machine with both hands. One hand of the operator normally holds a gripping handle mounted on the housing, while the other hand engages a housing control hanclle for actuating a trigger throttle mechanism.
In some instances of cutting operation, the cutting cha;n may encounter resistance of a type causing the cutter bar to kick upwardly in a manner commonly referred to as "kickback".
Generally the main method for dealing with this ! "kickback" phenomenon has been to incorporate a chain brake which can be actuated at the onset of "kickback", stopping the chain by means of the brake before contact with the operator.
Most chain saws incorporate a centrifugal clutch between the engine and the chain drive sprocket. A
typical clutch design is illustrated in U.S. Patent No.
2, 9479 411, Centrifugal Clutch Actuator and Spring Retainer by R. L. Collins, Since the driYe sprocket is usually attached to the clutch housing9 the housing typically ser~es as the brake drum for most braking systems.
An example of such a braking system can be found 1~ in U.S. Patent No. 3,739,475, Chain Saw Safety Me-thod And - Apparatus by H. ~. Moore. Moore provides a yoke, incorporating brake shoes p`iYotally mounted at each end, which is rotatably mounted to the saw housing. The brake shoes have tapered surfaces adapted to engage housing mounted lugs and thus when the yoke is rotated the brake shoes are forced into contact with the periphery of the clutch housing. The yoke is coupled to a saEety bar located on the front gripping handle by means of a push rod and is spring biased to a position which retracts the brake shoes. Should the saw "kickback" and the hand or arm oE the operator strike the safety bar the brake shoes are driven into the clutch drum and wedged in place stopping chain rotation.
This design has several disadvantages, one of 25 which is that once the brake shoes are engaged they may be difficult to retract because they are wedged in place.
Furthermore the braking system is re]atively heavy.
Another example of the use of brake shoes can be Eound in U.S. Patent No. 3,793,727, Chain Saw Safety Method And 30 Apparatus by H. E. Moore.
Su~sequent designs have used flexible brake bands, i.e. UOS. Patent No. 3,776,331, Brake-Device For Power Saws by L. Gustafsson. In this design a flexible band is loosely wrapped around the clutch drum with one end of the band attached to the housing. The opposite end 7~
k is attached to one end of a lever arm &~ is pivotally mounted to the housing in front of the gripping handle with one end of the flexible brake band attached directly thereto. Pivotally attached to the lever is a latch adapted to engage a pin mounted in the housing. A spring mounted between the leYer and housing biases the latch to the lat~hed position and also biases the lever to the braking position~ Upon movement of the leYer the latch is forced past the pin and the spring continues to bias the 10 lever to the braking position. While this design is simpler than the aforementioned designs, when the brake assembly is in the non-braking position, the spring bîases the latch to the latching position and the lever to the braking position~ This makes the proper selection of 15 spring strength difficult. If the spring produces too much force it will be difficult to unlatch the safety lever and if it is too weak the braking force produced by the flexible band may not be sufficient to,stop the chain 'as rapidly as may be desired.
Therefore it is desirable to have the sp,ring bias the saety lever (sensing arm) in the non-braking position only when it is in the non-braking position and to only bias the lever to the,braking position only when it is in that position. This ensures that there is always a 25 positive force maintaining the desired position. This was - accomplished in a design disclosed in U.S. Patent No.
An example of such a braking system can be found 1~ in U.S. Patent No. 3,739,475, Chain Saw Safety Me-thod And - Apparatus by H. ~. Moore. Moore provides a yoke, incorporating brake shoes p`iYotally mounted at each end, which is rotatably mounted to the saw housing. The brake shoes have tapered surfaces adapted to engage housing mounted lugs and thus when the yoke is rotated the brake shoes are forced into contact with the periphery of the clutch housing. The yoke is coupled to a saEety bar located on the front gripping handle by means of a push rod and is spring biased to a position which retracts the brake shoes. Should the saw "kickback" and the hand or arm oE the operator strike the safety bar the brake shoes are driven into the clutch drum and wedged in place stopping chain rotation.
This design has several disadvantages, one of 25 which is that once the brake shoes are engaged they may be difficult to retract because they are wedged in place.
Furthermore the braking system is re]atively heavy.
Another example of the use of brake shoes can be Eound in U.S. Patent No. 3,793,727, Chain Saw Safety Method And 30 Apparatus by H. E. Moore.
Su~sequent designs have used flexible brake bands, i.e. UOS. Patent No. 3,776,331, Brake-Device For Power Saws by L. Gustafsson. In this design a flexible band is loosely wrapped around the clutch drum with one end of the band attached to the housing. The opposite end 7~
k is attached to one end of a lever arm &~ is pivotally mounted to the housing in front of the gripping handle with one end of the flexible brake band attached directly thereto. Pivotally attached to the lever is a latch adapted to engage a pin mounted in the housing. A spring mounted between the leYer and housing biases the latch to the lat~hed position and also biases the lever to the braking position~ Upon movement of the leYer the latch is forced past the pin and the spring continues to bias the 10 lever to the braking position. While this design is simpler than the aforementioned designs, when the brake assembly is in the non-braking position, the spring bîases the latch to the latching position and the lever to the braking position~ This makes the proper selection of 15 spring strength difficult. If the spring produces too much force it will be difficult to unlatch the safety lever and if it is too weak the braking force produced by the flexible band may not be sufficient to,stop the chain 'as rapidly as may be desired.
Therefore it is desirable to have the sp,ring bias the saety lever (sensing arm) in the non-braking position only when it is in the non-braking position and to only bias the lever to the,braking position only when it is in that position. This ensures that there is always a 25 positive force maintaining the desired position. This was - accomplished in a design disclosed in U.S. Patent No.
3,934j345, Snap-Acting Over Center Chain Saw Safety Brake And Method Of Operation Thereof by S. Hirschkoff. In this design a safety handle is typically mounted to the 'saw 30 housing and in the actuated position holds a flexible brake band into frictional contact with the clutch drum.
A gu;de rod is both slideably and pivotally mounted to the housing at one end and at the opposite 'end to a curved slot or grooYe. The rod i5 spring biased toward the safety handle. l`he positional relationship of the slot, rod and }-andle pi~ot point are such that in the unbraked position the thrust angle of the spring is below the pivot point of the safety handle biasing the safety handle toward the unbraked position and when the safety 5 handle is in the braked posltion the thrust angle of the spring is above the pivot point biasing the safety handle toward the ~braked position. While this design achieves 1'~3 the over center latch function it is heavy and somewhat expensive to manufacture.
All the designs discussed above are actuated by an arm or hand or other appendage of the operator during kickbac~. However, there have been designs which have attempted to sense the angular acceleration of the chain saw upon kickback and to stop the chain without the 15 operator having to manually move the safety lever, an example of which can be found in U.S. Patent No.
3J923,126, ~and Type Brake In A Chain Saw by E. J.
Bidenset. In this design an inertia sensor in the form of a guide mernber and a first lever connected together are 20 rotatably mounted in the saw housing. The first lever engages a second lever also rotatably mounted in the housing and the two are spring biased toward each other.
The seco-nd lever has an arm which abuts against the end of a brake band spring biased to the braking position. In 25 operation, when kickback occurs the inertia loads on the guide member and first lever cause them to move Eree of the brake band end. In another embodiment the second lever is attached directly to the end of the 1exible brake band and thus rotation of the second lever directly 30 brakes the chain.
This design is complicated and expensive to manufacture and re~uires a lot of care to assemble. Since the guide member is also acting as a safety bar capable of actuating~the brake upon contact with the operator's hand 35 or arm it will be difficult to set the proper triggering 7~
level. This is ~ecause t~e inertia ~ue to 7'kickback" is going to be considerahly smaller ~ n the force applied by the operator. If the force level is indeed ~ery low the saw will be subjected to continuous actuation of the brake 5 by the casual touching of the guide member.
Other chain saw braking systems of interest are shcwn in U.S. Patent Nc. 3~937~306J Automatic Brake Actuator For A Chain Saw by Ulf Vilhein Naslund et al;
3J 964,3339 Safety Braking Mechanism For A Portable Chain 10 Saw by S. Hirschkoff; and 4,121~339, Safety Brake Mechanism For Chain Saw by M. Nikolich.
Therefore it is a prima~y object of this invention to provide a chain brake for a chain saw that is compact, light in weight and rel;able.
- Another object of-this invention is to provide a chain brake for a chain saw wherein the safety bar is biased between one or the other of two positions, one being the non-braking position an~ the other being the braking position.
A further object of this invention is to provide a chain brake for a chain saw that requires only a small movement of the safe~y bar to achieve full braking effect.
A still further object of this invention is to provîde a chain brake for a chain saw which provides both manual and auto~atic chain braking capabilities.
The invention provides a safety brake assembly for a chain saw which is clesigned prlmarily to protect the operator from injury due to "Kickback." Generally, most chain saws comprise a housing means having a grippiny handle mounted thereon; an engine or motor means carried by the housing; a cutting chain, a support bar means projecting forwardly from the housing means, for 7~
s~pporting cutting chain movement; and a rotation transmitting assernbly or means ~or dri~ing the cutting chain. The safety braking assembly or means of the present invention compriSes a sensing ~rm or means 5 pivotally mounted to the housing, the sensing arm in one embodiment having a protrusion in the form of a pin mounted thereto. A portion of the sensing arm is located in front of the gripping handle during operation of the chain saw and is arranged to be swung from a first 10 position to a second position in response to being struck by an appendage of the operator. A flexible brake band is disposed around the peripheral surface Qf rotation transmitting means or brake drum, and has a first end anchored to the housing and a second end coupled to the 15 sensing arm, preferably by means of the pin, in a manner - such that when the sensing arm moves from the first position to the second position the flexible brake band is moved from a position free of the brake drum to a ~rictional braking relationship therewith. A latch ~hich 20 is rotatably mounted to the housing is adapted to engage the protrusion of the sensing bar. Biasing means (or a tension spring) is anchored at its first end to the latch, in such a manner that the latch yieldably holds the sensing arm in the first position when the sensing arm is 25 in that position and yieldably holds the sens;ng arm in the sec~nd position when the sensing arm is in that .positionP
Thus, when the appendage of an operator strikes the sensing arm typically due to the "kickback"
30 phenomenon, the sensing arm will move from the first position to the second position stopping chain movement prior to the cutting chain coming into contact with the operator.
Addi~ionally, an acceleration sensing assembly or 35 means can be incorporated as a second embodiment to sense 7~
the acceleration of the chain saw due to 'Ikickback''~
Preferably the acceleration sensing assembly comprises a bar having a cam mounted thereto, the bar being pivotally mounted to the housing. The aforementioned latch is 5 provided with a lever in disengageable contact with the cam. When "kickback" occurs the chain saw will rotate in relationship to the bar because the bar has inertia and tends to resist the acceleration. This will cause the cam to rotate the lever which in turn will cause the sensing 10 arm to move from the first position to the second position stoppin~ the chain.
In a third embodiment a first pin is instead mounted on the latch, and ~he sensing arm incorporates a different protrusion, one having a U shaped groove coupled 15 to this first pin. The second end of the flexible brake band in this third embodiment is ~ypically coupled to a second pin mounted on the latch.
A fourth embodiment of the present invention incorporates the above-described acceleration sensing 20 assembly with the latch mechanism of the third embodiment.
Illustrated in FIGURE 1 is a side elevation view of a portion of a chain saw in accordanee with the present invention, Illustrated in FIGURE 2 is a front view of the chain saw shown in FIGURE l;
Illustrated in FIGURE 3 is a side view of a safety braking system.forming a part of the chain saw, with the brakin~ system being in a non braking position;
Illustrated in FIGURE 4 is an end view of the safety braking system, viewed along line 4-4 shown in FIGURE 1.
Illustrated in FIGURE 5 is a view similar to FIGURE 3 dep;cting the safety braking system in a braking position;
Illustrated..in FIGURE 6 is a view similar to FIGURE 3 showing a second embodiment of the safety braking system i.n a both non-braking and bra~ing position, Illustrated in FIGURE 7 is a side elevation view of a portion of a chain saw showing a third embodiment of the present invention.
Illustrated in FIGURE 8 is a side view of the safety braking system shown in FIGURE 7 in the braking position;
and Illustrated in FIGURE 9 is a side ~iew of the safety braking system shown in FIGURE 7 illustrating a fourth embodiment of the present invention in both a non-bra~ing and braking position.
Illustrated in FIGURE 1 is a side eleYation view of a portable chain saw, while illustrated in FIGURE 2 is a front view of the chain saw shown in FIGURE 1. The chain saw 10 includes a housing 12 which carries an internal combustion engine or motor means (not shown) ~8~
in a conveTItional fashion. The housing 12 incllJdes a control handle 14 mounted at ~he rear of the housing and a gripping handle or means 16 mounted near the fr~nt of the housing. The gripping handle includes top and side 5 portions 18, 20 and 22, respectively.
A guide bar or support means 24 projects forwardly from the housing 12 and supports a saw chain or cutting chain 26 for endless movernent therearound. The cutter chain is driven by a suitable power transmission or 10 rotation transmitting means from the internal combustion engine. The power transrnission per se does not constitute a part of the present invention, hence any suitable - conventional power transmission assembly may be utilized, such as those disclosed, for example, in U.S. Patent ~o.
15 2,9~7,3g9, Centrifugally Activated ~riction Clutch by H.
- E. Moore, and U.S. Patent No. 3,385,411, Centrifugal Clutch Actua~or And Spring Retainer by R. L. Collins.
Usually, the power transmission includes a chain sprocket wheel which is rotated by the engine drive shaft 20 and around which is arranged the cutting chain 26.
Rotation of the chain sprocket wheel drives the cutting chain in endless fashion around the guide bar 24.
During use of the çhain saw 10 an operator grasps the control handle 14 with one hand and the gripping 25 handle 16 with the other hand. The gripping handle 16 is primarily used to manipulate and apply pressure to the chain saw, while the control handle 14 is utilized to stabilize the saw and control the rate of travel of the cutting chain through operation of a trigger throttle 28.
The operator is able to grasp various portions of the gripping handle 16 in order to properly orient the cutting chain.
As noted earlier, the "kickback" phenomenon can occur without warning. In order to minimize the effects 4t7~
of kickback the present ;nvention involYes the provision of a chain saw bralcing system.
In one preferred embodiment the safety braking system or means9 generally designated by numeral 29, includes a sensing arm or means 30 which is pivotally mounted for swinging movement about an axis of rotation 31. The sensing arm is generally an inverted U-shaped member ~see ~IGURE 2) haYing essentially vertically extending side sections 32, 33, and a horizontally extending top section 34. The side section 32 is pivotally mounted at end 3~ to the housing 12 by a bolt 36 and pivots about axis 31. Thus ~he sensing arm is located in front of the gripping handle 16, The other side portion 33 is also pivotally mounted on the housing.
In short, the sensing arm 30 is arranged to lie between the gripping handle 16 and the cutting chain 26, to be engaged by an arm or hand of an operator. In any event, it will be appreciated that the sensing arm 30 is deployed to swing forwardly upon being strl-ck by an operator's appendage.
Still referring to ~IGURES 1 and 2, and t additionally to FIGURES 3 and 4, it can be seen that the sensing arm 30 includes a protrusion in the form of a rigid pin 38 which extends through a notch 39 in housing 12.
The brake assembly 29 includes a ~lexible brake band 40 which is anchored at a first end 41 by a pin 42 attached to the housing 12. The brake band 40 is disposed about the peripheral surface 44 of a brake drum 46 and is attached at its second end 47 to the pin 38. The brake drum 46 comprises a rotary element that is coupled to the power transmission (not shown) of the cha;n saw such that braking forces which are applied to the drurn will serve to slow the cutting chain. For example, the drum ~6 can be coupled to a shaft 48 driven hy the engine or to a sprocket wheel which drives the cutting chain.
Alternatively, in those instances wherein centrifugal c~utches are utilized, (such a~ are disclosed in the previously mentioned Moore et al and Collins Patents) the cup of the clutch may advantageously serve as the brake drum. In any event, as the chain saw engine and power transmission rotate the cutting chain, the drum 46 will also be rotated. Should a brakin~ force be applied to the drum 46, such force will be transmitted in a manner to brake the cutting chain. It will be noted, however that the brake drum is, under normal operating conditions, ree-turning and does not interfere with or place limitations upon the cutting chain power transmission.
A latch 50 is rotatably mounted to the housing 12 by means of a pin 51 and thus has an axis of rotation 52.
The latch 50 is adapted to be engaged by sensing arm 30, which is accomplished by incorporating a notch 54 in the 20 latch 50 positioned to engage the pin 38, (thus pin 38 acts as a latch enganement means for the sensing arm).
Biasing means, in the form of a tension spring 60, is mounted at its first end 62 to the housing 12 by means of fastener 64 and by its second end 66 engaging a notch 67 25 on the latch 50.
Thus as illustrated in FI~S 3 and 4, with the sensing arm 30 in the non-braking or first position, the pin 38 positions the latch 50 so that the ~orce produced by the spring 60 lies along the force axis 70 (on the same 30 side of the axis of rotation 52 as the pin 38). Thus the sensing arm 30 is yieldably held in the first position.
The spring 60 will yieldably hold the sensing arm 30 in the first position as long as the force axis 70 of the ~_~8~q6 spring remains on the same side of ~he axis of rotation 52 of the pin 51. Of course, the brake band 40 remains out of a frictional braking relationship with the brake drum 46.
FIGUR~ 5, which is a view similar to FIGURE 3~
illustrates the sensing arm 30 in the second position or braking position~ This will occur if the operator moves the sensing arm 30 due to h;s or her appendage striking the sensing arm during the previously discussed "kickback"
phenomenon. When the sensing arm 30 is moved from the first position ~o the second or braking position the pin 38 attached thereto being in engagement with notch 54 of the latch 50 causes the latch to rotate (as shown in FIGURE 5, in a counter-clock wise direction). As the pin 38 translates, the braXe band 40 is brought into contact with ~he surface 44 of the bra~e drum 46 preventing the rotation of the drum and stopping the chain 26.
Simultaneously, the latch 50 shifts to a position wherein the force axis 70 of the spring 60 is transferred to the opposite side of the axis of rotation 52 of the latch 50. -In this position the spring 60 tends to yieldably hold the sensing arm 30 in the second position.
To reset the sensing arm 30 ~o the first position the operator need only apply a force to the sensing arm sufficient to overcome the force of the spring 60.
Although such a braking system 29 has many advantages, for example, low cost, high reliability, lightness in weight, and the capabilities to provide a yieldabl~ holding force to maintain the sensing arm 30 when the safety arm is either in the first or second position, the safety characteristics of the braking system can be further improved by incorporating a second mechanism for braking the chain that does not require an appendage of the operator to strike the safety arm. As illustrated in FIGURE ~ an acceleration sensing system, generally designated by numeral 80, can be proYided which will sense the acceleration of the chain saw due to "kicXback". The acceleration sensing system or 5 acceleration sensor means 80 comprises a sensing bar 81 rotatably attached to the housing 12 by a fastener ~2.
The sensing bar 81 incorporates a cam surface 83. A latch 50' is provided with a lever ~rm 84 adapted to contact the cam surface 83. The sensing bar 81 is provided with a lO weight 86. ~hile the weight 86 can be fixed in position for reasons that will be subsequently discussed, it may be desirable that it moveably engage the sensing arm 81 and be selectively fixable in a predetermined position on said sensing bar 81 by fastening means or se~ screw 87.
Thus, during "kickback" the bar 81 will resist the acceleration due to its inertia, ~hich will cause the cam surface 83 to rotate relative to the chain saw. This will cause the latch 50' to rotate to a position where the spring 60's force axis 70 mcves to the side opposite the 20 axis of rotation 52~, thus causing the spring 60 to yieldably hold the sensing arm 3~ in the second position via the latch 50' and move the brake band 40 into contact-with surface 44 of the brake drum 46. Thus, with incorporation of the acceleratlon sensing system 80, an 25 appendage of the operator need not make contact with the sensing arm 30 to stop the chain. ~urthermore by proper selection of the size of the weight 86 and its distance from the pivot point, the amount of "kickbackl' acceleration to be tolerated can be set at different 30 values~
Illustrated in FIGURE 7 is a side elevation view of a portion of a chain saw showing a third embodiment of the safety braking system. Referring to FIGURES 7 and 8, the chain saw is generally designated by numeral 200 and 7~i includes a housing 201 having a front gripping handle 202 and a brake assembly generally designated by numeral 203.
The brake assembly 203 comprises a sensing arm 204 mounted on the housing 201 and rotatable about an axis of rota-tion 5 205 from a first position shown in FIGURE 7 to a second position shown in FIGIJRE 8. The scnsing arm 204 incorporates another form of the protrusion described hereinabove, but in this embodiment taking the form of a member 206 having an end 207 with a first groove 208. The 10 brake assembly 203 further includes another form of latch or lever 210 rotatably mounted to the housing 200 about axis of rotation 211~ The lever 210 has a first pin 214 mounted thereto in engagement with first groove 208 on the ~nember 206 of the sensing arm 204. A flexible brake band 216 is anchored at its first end 218 to a housin~ pin 220 mounted in the housing 201, it is disposed about the peripheral surface 22Z of a brake drum 224 and is connected at its second 226 ~o a second pin 228 moun~ed on the leYe:r 210.
A s;pring 230 is mounted at its first end 232 to housing 201 and at its second end to a second groove 236 on the lever 210.` Thus, as in the pre~ous case of the chain brake system 29 illustrated in FIGURES 1-~, when the sensing arm 204 moves from the first postion or 25 non-brak;ng position (FIGURE 7) to the second position (FIGUR:E 8), the groove 208 on member 206 rota~es the lever 210 counterclockwise via Eirst pin 214 causing the chain to stop. Meanwhile, this movelnent in turn causes the thrust axis 2'10 o~f the spring 230 to move from a position 30 tending to hold the sensing arm in the first position and the braJce band 216 free of peripheral surface 222 of brake drum 224, to a second position tshown in ~IGURE 8) when the thrust axis 240 of the spring 230 is on the opposite side of the axis of rotation 2:L1 of the lever 210.
~8~
Thus, t~e spring 230 now ten~s to hold the sensing arm 204 in the second position and the brake band 216 ;nto contact with the peripheral surface 222 of the drum 224.
A fourth embodiment of the present inYention i5 shown in FIGURE 9, where the lever 210 optionally incorporates a lever arm 244 in contact with an optional accelerating sensing system 246, which is similar to the accelerating sensing system 80 illustrated in FIGURE 6, and operates in a similar fashion. Accelerating sensing system ?46 includes a sensing bar 248 rotatably attached to housing 201 by a fastener 250. The bar 248 incorporates a cam surface 252, which contacts the lever arms 244. Sensing bar 248 is pro~ided with a weight 254 movably engageable with the bar 248 and selectively lS fixable in place thereto by set screw 256. Thus, during "kickhack" the bar 248 will resist the acceleration due to its inertia, which will cause the cam surface 252 to rotate relative to the chain saw. This will cause the lever 210 to rotate to a position where the force axis 240 of spring 230 moves ~o the side opposite the axis of rotation ~ , thus ca~s~ng the spring Z30 to yieldably . hold the sensing arm ~4~ in the second or braking position via the lever 210, and move the brake band 216 into contact with surface 222 of the brake drum 224. Thus, 25 with incorporation of the acceleration sensing system 246, an appendage of ~he~ operator need not make contact with the sensillg arm ~ to stop the chain. Again by proper selection of the size of the weight 254 and its distance from the pivot point, the amount of "kickback"
3~ acceleration to be tolerated can be set at differen~
values.
A gu;de rod is both slideably and pivotally mounted to the housing at one end and at the opposite 'end to a curved slot or grooYe. The rod i5 spring biased toward the safety handle. l`he positional relationship of the slot, rod and }-andle pi~ot point are such that in the unbraked position the thrust angle of the spring is below the pivot point of the safety handle biasing the safety handle toward the unbraked position and when the safety 5 handle is in the braked posltion the thrust angle of the spring is above the pivot point biasing the safety handle toward the ~braked position. While this design achieves 1'~3 the over center latch function it is heavy and somewhat expensive to manufacture.
All the designs discussed above are actuated by an arm or hand or other appendage of the operator during kickbac~. However, there have been designs which have attempted to sense the angular acceleration of the chain saw upon kickback and to stop the chain without the 15 operator having to manually move the safety lever, an example of which can be found in U.S. Patent No.
3J923,126, ~and Type Brake In A Chain Saw by E. J.
Bidenset. In this design an inertia sensor in the form of a guide mernber and a first lever connected together are 20 rotatably mounted in the saw housing. The first lever engages a second lever also rotatably mounted in the housing and the two are spring biased toward each other.
The seco-nd lever has an arm which abuts against the end of a brake band spring biased to the braking position. In 25 operation, when kickback occurs the inertia loads on the guide member and first lever cause them to move Eree of the brake band end. In another embodiment the second lever is attached directly to the end of the 1exible brake band and thus rotation of the second lever directly 30 brakes the chain.
This design is complicated and expensive to manufacture and re~uires a lot of care to assemble. Since the guide member is also acting as a safety bar capable of actuating~the brake upon contact with the operator's hand 35 or arm it will be difficult to set the proper triggering 7~
level. This is ~ecause t~e inertia ~ue to 7'kickback" is going to be considerahly smaller ~ n the force applied by the operator. If the force level is indeed ~ery low the saw will be subjected to continuous actuation of the brake 5 by the casual touching of the guide member.
Other chain saw braking systems of interest are shcwn in U.S. Patent Nc. 3~937~306J Automatic Brake Actuator For A Chain Saw by Ulf Vilhein Naslund et al;
3J 964,3339 Safety Braking Mechanism For A Portable Chain 10 Saw by S. Hirschkoff; and 4,121~339, Safety Brake Mechanism For Chain Saw by M. Nikolich.
Therefore it is a prima~y object of this invention to provide a chain brake for a chain saw that is compact, light in weight and rel;able.
- Another object of-this invention is to provide a chain brake for a chain saw wherein the safety bar is biased between one or the other of two positions, one being the non-braking position an~ the other being the braking position.
A further object of this invention is to provide a chain brake for a chain saw that requires only a small movement of the safe~y bar to achieve full braking effect.
A still further object of this invention is to provîde a chain brake for a chain saw which provides both manual and auto~atic chain braking capabilities.
The invention provides a safety brake assembly for a chain saw which is clesigned prlmarily to protect the operator from injury due to "Kickback." Generally, most chain saws comprise a housing means having a grippiny handle mounted thereon; an engine or motor means carried by the housing; a cutting chain, a support bar means projecting forwardly from the housing means, for 7~
s~pporting cutting chain movement; and a rotation transmitting assernbly or means ~or dri~ing the cutting chain. The safety braking assembly or means of the present invention compriSes a sensing ~rm or means 5 pivotally mounted to the housing, the sensing arm in one embodiment having a protrusion in the form of a pin mounted thereto. A portion of the sensing arm is located in front of the gripping handle during operation of the chain saw and is arranged to be swung from a first 10 position to a second position in response to being struck by an appendage of the operator. A flexible brake band is disposed around the peripheral surface Qf rotation transmitting means or brake drum, and has a first end anchored to the housing and a second end coupled to the 15 sensing arm, preferably by means of the pin, in a manner - such that when the sensing arm moves from the first position to the second position the flexible brake band is moved from a position free of the brake drum to a ~rictional braking relationship therewith. A latch ~hich 20 is rotatably mounted to the housing is adapted to engage the protrusion of the sensing bar. Biasing means (or a tension spring) is anchored at its first end to the latch, in such a manner that the latch yieldably holds the sensing arm in the first position when the sensing arm is 25 in that position and yieldably holds the sens;ng arm in the sec~nd position when the sensing arm is in that .positionP
Thus, when the appendage of an operator strikes the sensing arm typically due to the "kickback"
30 phenomenon, the sensing arm will move from the first position to the second position stopping chain movement prior to the cutting chain coming into contact with the operator.
Addi~ionally, an acceleration sensing assembly or 35 means can be incorporated as a second embodiment to sense 7~
the acceleration of the chain saw due to 'Ikickback''~
Preferably the acceleration sensing assembly comprises a bar having a cam mounted thereto, the bar being pivotally mounted to the housing. The aforementioned latch is 5 provided with a lever in disengageable contact with the cam. When "kickback" occurs the chain saw will rotate in relationship to the bar because the bar has inertia and tends to resist the acceleration. This will cause the cam to rotate the lever which in turn will cause the sensing 10 arm to move from the first position to the second position stoppin~ the chain.
In a third embodiment a first pin is instead mounted on the latch, and ~he sensing arm incorporates a different protrusion, one having a U shaped groove coupled 15 to this first pin. The second end of the flexible brake band in this third embodiment is ~ypically coupled to a second pin mounted on the latch.
A fourth embodiment of the present invention incorporates the above-described acceleration sensing 20 assembly with the latch mechanism of the third embodiment.
Illustrated in FIGURE 1 is a side elevation view of a portion of a chain saw in accordanee with the present invention, Illustrated in FIGURE 2 is a front view of the chain saw shown in FIGURE l;
Illustrated in FIGURE 3 is a side view of a safety braking system.forming a part of the chain saw, with the brakin~ system being in a non braking position;
Illustrated in FIGURE 4 is an end view of the safety braking system, viewed along line 4-4 shown in FIGURE 1.
Illustrated in FIGURE 5 is a view similar to FIGURE 3 dep;cting the safety braking system in a braking position;
Illustrated..in FIGURE 6 is a view similar to FIGURE 3 showing a second embodiment of the safety braking system i.n a both non-braking and bra~ing position, Illustrated in FIGURE 7 is a side elevation view of a portion of a chain saw showing a third embodiment of the present invention.
Illustrated in FIGURE 8 is a side view of the safety braking system shown in FIGURE 7 in the braking position;
and Illustrated in FIGURE 9 is a side ~iew of the safety braking system shown in FIGURE 7 illustrating a fourth embodiment of the present invention in both a non-bra~ing and braking position.
Illustrated in FIGURE 1 is a side eleYation view of a portable chain saw, while illustrated in FIGURE 2 is a front view of the chain saw shown in FIGURE 1. The chain saw 10 includes a housing 12 which carries an internal combustion engine or motor means (not shown) ~8~
in a conveTItional fashion. The housing 12 incllJdes a control handle 14 mounted at ~he rear of the housing and a gripping handle or means 16 mounted near the fr~nt of the housing. The gripping handle includes top and side 5 portions 18, 20 and 22, respectively.
A guide bar or support means 24 projects forwardly from the housing 12 and supports a saw chain or cutting chain 26 for endless movernent therearound. The cutter chain is driven by a suitable power transmission or 10 rotation transmitting means from the internal combustion engine. The power transrnission per se does not constitute a part of the present invention, hence any suitable - conventional power transmission assembly may be utilized, such as those disclosed, for example, in U.S. Patent ~o.
15 2,9~7,3g9, Centrifugally Activated ~riction Clutch by H.
- E. Moore, and U.S. Patent No. 3,385,411, Centrifugal Clutch Actua~or And Spring Retainer by R. L. Collins.
Usually, the power transmission includes a chain sprocket wheel which is rotated by the engine drive shaft 20 and around which is arranged the cutting chain 26.
Rotation of the chain sprocket wheel drives the cutting chain in endless fashion around the guide bar 24.
During use of the çhain saw 10 an operator grasps the control handle 14 with one hand and the gripping 25 handle 16 with the other hand. The gripping handle 16 is primarily used to manipulate and apply pressure to the chain saw, while the control handle 14 is utilized to stabilize the saw and control the rate of travel of the cutting chain through operation of a trigger throttle 28.
The operator is able to grasp various portions of the gripping handle 16 in order to properly orient the cutting chain.
As noted earlier, the "kickback" phenomenon can occur without warning. In order to minimize the effects 4t7~
of kickback the present ;nvention involYes the provision of a chain saw bralcing system.
In one preferred embodiment the safety braking system or means9 generally designated by numeral 29, includes a sensing arm or means 30 which is pivotally mounted for swinging movement about an axis of rotation 31. The sensing arm is generally an inverted U-shaped member ~see ~IGURE 2) haYing essentially vertically extending side sections 32, 33, and a horizontally extending top section 34. The side section 32 is pivotally mounted at end 3~ to the housing 12 by a bolt 36 and pivots about axis 31. Thus ~he sensing arm is located in front of the gripping handle 16, The other side portion 33 is also pivotally mounted on the housing.
In short, the sensing arm 30 is arranged to lie between the gripping handle 16 and the cutting chain 26, to be engaged by an arm or hand of an operator. In any event, it will be appreciated that the sensing arm 30 is deployed to swing forwardly upon being strl-ck by an operator's appendage.
Still referring to ~IGURES 1 and 2, and t additionally to FIGURES 3 and 4, it can be seen that the sensing arm 30 includes a protrusion in the form of a rigid pin 38 which extends through a notch 39 in housing 12.
The brake assembly 29 includes a ~lexible brake band 40 which is anchored at a first end 41 by a pin 42 attached to the housing 12. The brake band 40 is disposed about the peripheral surface 44 of a brake drum 46 and is attached at its second end 47 to the pin 38. The brake drum 46 comprises a rotary element that is coupled to the power transmission (not shown) of the cha;n saw such that braking forces which are applied to the drurn will serve to slow the cutting chain. For example, the drum ~6 can be coupled to a shaft 48 driven hy the engine or to a sprocket wheel which drives the cutting chain.
Alternatively, in those instances wherein centrifugal c~utches are utilized, (such a~ are disclosed in the previously mentioned Moore et al and Collins Patents) the cup of the clutch may advantageously serve as the brake drum. In any event, as the chain saw engine and power transmission rotate the cutting chain, the drum 46 will also be rotated. Should a brakin~ force be applied to the drum 46, such force will be transmitted in a manner to brake the cutting chain. It will be noted, however that the brake drum is, under normal operating conditions, ree-turning and does not interfere with or place limitations upon the cutting chain power transmission.
A latch 50 is rotatably mounted to the housing 12 by means of a pin 51 and thus has an axis of rotation 52.
The latch 50 is adapted to be engaged by sensing arm 30, which is accomplished by incorporating a notch 54 in the 20 latch 50 positioned to engage the pin 38, (thus pin 38 acts as a latch enganement means for the sensing arm).
Biasing means, in the form of a tension spring 60, is mounted at its first end 62 to the housing 12 by means of fastener 64 and by its second end 66 engaging a notch 67 25 on the latch 50.
Thus as illustrated in FI~S 3 and 4, with the sensing arm 30 in the non-braking or first position, the pin 38 positions the latch 50 so that the ~orce produced by the spring 60 lies along the force axis 70 (on the same 30 side of the axis of rotation 52 as the pin 38). Thus the sensing arm 30 is yieldably held in the first position.
The spring 60 will yieldably hold the sensing arm 30 in the first position as long as the force axis 70 of the ~_~8~q6 spring remains on the same side of ~he axis of rotation 52 of the pin 51. Of course, the brake band 40 remains out of a frictional braking relationship with the brake drum 46.
FIGUR~ 5, which is a view similar to FIGURE 3~
illustrates the sensing arm 30 in the second position or braking position~ This will occur if the operator moves the sensing arm 30 due to h;s or her appendage striking the sensing arm during the previously discussed "kickback"
phenomenon. When the sensing arm 30 is moved from the first position ~o the second or braking position the pin 38 attached thereto being in engagement with notch 54 of the latch 50 causes the latch to rotate (as shown in FIGURE 5, in a counter-clock wise direction). As the pin 38 translates, the braXe band 40 is brought into contact with ~he surface 44 of the bra~e drum 46 preventing the rotation of the drum and stopping the chain 26.
Simultaneously, the latch 50 shifts to a position wherein the force axis 70 of the spring 60 is transferred to the opposite side of the axis of rotation 52 of the latch 50. -In this position the spring 60 tends to yieldably hold the sensing arm 30 in the second position.
To reset the sensing arm 30 ~o the first position the operator need only apply a force to the sensing arm sufficient to overcome the force of the spring 60.
Although such a braking system 29 has many advantages, for example, low cost, high reliability, lightness in weight, and the capabilities to provide a yieldabl~ holding force to maintain the sensing arm 30 when the safety arm is either in the first or second position, the safety characteristics of the braking system can be further improved by incorporating a second mechanism for braking the chain that does not require an appendage of the operator to strike the safety arm. As illustrated in FIGURE ~ an acceleration sensing system, generally designated by numeral 80, can be proYided which will sense the acceleration of the chain saw due to "kicXback". The acceleration sensing system or 5 acceleration sensor means 80 comprises a sensing bar 81 rotatably attached to the housing 12 by a fastener ~2.
The sensing bar 81 incorporates a cam surface 83. A latch 50' is provided with a lever ~rm 84 adapted to contact the cam surface 83. The sensing bar 81 is provided with a lO weight 86. ~hile the weight 86 can be fixed in position for reasons that will be subsequently discussed, it may be desirable that it moveably engage the sensing arm 81 and be selectively fixable in a predetermined position on said sensing bar 81 by fastening means or se~ screw 87.
Thus, during "kickback" the bar 81 will resist the acceleration due to its inertia, ~hich will cause the cam surface 83 to rotate relative to the chain saw. This will cause the latch 50' to rotate to a position where the spring 60's force axis 70 mcves to the side opposite the 20 axis of rotation 52~, thus causing the spring 60 to yieldably hold the sensing arm 3~ in the second position via the latch 50' and move the brake band 40 into contact-with surface 44 of the brake drum 46. Thus, with incorporation of the acceleratlon sensing system 80, an 25 appendage of the operator need not make contact with the sensing arm 30 to stop the chain. ~urthermore by proper selection of the size of the weight 86 and its distance from the pivot point, the amount of "kickbackl' acceleration to be tolerated can be set at different 30 values~
Illustrated in FIGURE 7 is a side elevation view of a portion of a chain saw showing a third embodiment of the safety braking system. Referring to FIGURES 7 and 8, the chain saw is generally designated by numeral 200 and 7~i includes a housing 201 having a front gripping handle 202 and a brake assembly generally designated by numeral 203.
The brake assembly 203 comprises a sensing arm 204 mounted on the housing 201 and rotatable about an axis of rota-tion 5 205 from a first position shown in FIGURE 7 to a second position shown in FIGIJRE 8. The scnsing arm 204 incorporates another form of the protrusion described hereinabove, but in this embodiment taking the form of a member 206 having an end 207 with a first groove 208. The 10 brake assembly 203 further includes another form of latch or lever 210 rotatably mounted to the housing 200 about axis of rotation 211~ The lever 210 has a first pin 214 mounted thereto in engagement with first groove 208 on the ~nember 206 of the sensing arm 204. A flexible brake band 216 is anchored at its first end 218 to a housin~ pin 220 mounted in the housing 201, it is disposed about the peripheral surface 22Z of a brake drum 224 and is connected at its second 226 ~o a second pin 228 moun~ed on the leYe:r 210.
A s;pring 230 is mounted at its first end 232 to housing 201 and at its second end to a second groove 236 on the lever 210.` Thus, as in the pre~ous case of the chain brake system 29 illustrated in FIGURES 1-~, when the sensing arm 204 moves from the first postion or 25 non-brak;ng position (FIGURE 7) to the second position (FIGUR:E 8), the groove 208 on member 206 rota~es the lever 210 counterclockwise via Eirst pin 214 causing the chain to stop. Meanwhile, this movelnent in turn causes the thrust axis 2'10 o~f the spring 230 to move from a position 30 tending to hold the sensing arm in the first position and the braJce band 216 free of peripheral surface 222 of brake drum 224, to a second position tshown in ~IGURE 8) when the thrust axis 240 of the spring 230 is on the opposite side of the axis of rotation 2:L1 of the lever 210.
~8~
Thus, t~e spring 230 now ten~s to hold the sensing arm 204 in the second position and the brake band 216 ;nto contact with the peripheral surface 222 of the drum 224.
A fourth embodiment of the present inYention i5 shown in FIGURE 9, where the lever 210 optionally incorporates a lever arm 244 in contact with an optional accelerating sensing system 246, which is similar to the accelerating sensing system 80 illustrated in FIGURE 6, and operates in a similar fashion. Accelerating sensing system ?46 includes a sensing bar 248 rotatably attached to housing 201 by a fastener 250. The bar 248 incorporates a cam surface 252, which contacts the lever arms 244. Sensing bar 248 is pro~ided with a weight 254 movably engageable with the bar 248 and selectively lS fixable in place thereto by set screw 256. Thus, during "kickhack" the bar 248 will resist the acceleration due to its inertia, which will cause the cam surface 252 to rotate relative to the chain saw. This will cause the lever 210 to rotate to a position where the force axis 240 of spring 230 moves ~o the side opposite the axis of rotation ~ , thus ca~s~ng the spring Z30 to yieldably . hold the sensing arm ~4~ in the second or braking position via the lever 210, and move the brake band 216 into contact with surface 222 of the brake drum 224. Thus, 25 with incorporation of the acceleration sensing system 246, an appendage of ~he~ operator need not make contact with the sensillg arm ~ to stop the chain. Again by proper selection of the size of the weight 254 and its distance from the pivot point, the amount of "kickback"
3~ acceleration to be tolerated can be set at differen~
values.
Claims (31)
1. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless movement, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, and safety braking means for stopping said cutting chain, said safety braking means com-prising:
a) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
b) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said protrusion in a manner such that when said sensing arm means moves from said first position to said second position said flexible band brake is moved from a position free of said rotation transmitting means to a frictional braking relationship with said rotation transmitting means;
c) a latch mounted on said housing means, said latch rotatable about an axis of rotation and receivingly engaging said protrusion of said sensing arm means; and d) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said sensing arm means to said first position when said sensing arm means is in said first position, and for yieldably urging said sensing arm means to said second position when said sensing arm means is in said second position.
a) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
b) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said protrusion in a manner such that when said sensing arm means moves from said first position to said second position said flexible band brake is moved from a position free of said rotation transmitting means to a frictional braking relationship with said rotation transmitting means;
c) a latch mounted on said housing means, said latch rotatable about an axis of rotation and receivingly engaging said protrusion of said sensing arm means; and d) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said sensing arm means to said first position when said sensing arm means is in said first position, and for yieldably urging said sensing arm means to said second position when said sensing arm means is in said second position.
2. The chain saw of Claim 1, wherein said second end of said biasing means is connected to said latch on the same side of said axis of rotation of said latch as said protrusion of said sensing arm means when said sensing arm means is in said first position, and on the opposite side of said axis of rotation when said sensing arm means is in said second position.
3. The chain saw of Claim 1, wherein said protru-sion comprises a pin on said sensing arm means and said latch includes a first groove receivable of said pin.
4. The chain saw of Claim 3, wherein said second end of said flexible brake band is connected to said pin.
5. The chain saw of Claim 4, wherein said latch includes a second groove engageable with said biasing means and said second end of said biasing means is connected to said latch by engagement with said second groove.
6. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless movement, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, said safety braking means for stopping said cutting chain, and safety braking means compris-ing:
a) acceleration sensing means, mounted on said housing means, and having a cam, for sensing the acceleration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value;
b) a latch mounted on said housing means, said latch rotatable about an axis of rotation, said latch having a lever arm adapted to disengageably contact said cam, said latch further having a protrusion mounted thereon; said latch being arranged to move from a first position wherein said lever arm is in contact with said cam to a second position wherein said lever arm is disengaged from said cam when said cam is moved from said first cam position to said second cam position;
c) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said protrusion in a manner such that when said cam moves from said first cam position to said second cam position, and hence said latch moves from said first position to said second position, said flexible brake band is moved from a position free of said rotation transmitting means to a frictional braking relationship with said rotation transmitting means; and d) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said latch to said first position when said cam is in said first cam position, and for yieldably urging said latch to said second position when said cam is in said second position, wherein said second end of said biasing means is connected to said latch on the same side of said axis of rotation of said latch as said protrusion when said cam is in said first position, and on the opposite side of said axis of rotation when said cam is in said second position.
a) acceleration sensing means, mounted on said housing means, and having a cam, for sensing the acceleration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value;
b) a latch mounted on said housing means, said latch rotatable about an axis of rotation, said latch having a lever arm adapted to disengageably contact said cam, said latch further having a protrusion mounted thereon; said latch being arranged to move from a first position wherein said lever arm is in contact with said cam to a second position wherein said lever arm is disengaged from said cam when said cam is moved from said first cam position to said second cam position;
c) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said protrusion in a manner such that when said cam moves from said first cam position to said second cam position, and hence said latch moves from said first position to said second position, said flexible brake band is moved from a position free of said rotation transmitting means to a frictional braking relationship with said rotation transmitting means; and d) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said latch to said first position when said cam is in said first cam position, and for yieldably urging said latch to said second position when said cam is in said second position, wherein said second end of said biasing means is connected to said latch on the same side of said axis of rotation of said latch as said protrusion when said cam is in said first position, and on the opposite side of said axis of rotation when said cam is in said second position.
7. The chain saw of Claim 6, wherein said accele-ration sensing means having a cam comprises an arm pivotally attached to said housing means having a cam attached thereto and a weight member mounted on said arm.
8. The chain saw of Claim 7, wherein said weight member is movably mounted on said arm and further including fastening means for fixing said weight member in a predeter-mined position on said arm.
9. The chain saw of Claim 6, wherein said protru-sion comprises a pin on said latch and said second end of said flexible brake band is connected to said pin.
10. The chain saw of Claim 6, wherein said latch includes a groove engageable with said biasing means and said second end of said biasing means is connected to said latch by engagement with said second groove.
11. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless movement, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, and safety braking means for stopping said cutting chain, said safety braking means com-prising:
a) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, said protrusion including a first groove, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
b) a latch mounted on said housing means, said latch rotatable about an axis of rotation, said latch having a first pin and a second pin mounted thereon, said first pin being in engagement with said first groove, said latch being arranged to move from a first latch position to a second latch position when said sensing arm means is moved from said first position to said second position;
c) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said second pin in a manner such that when said sensing arm means moves from said first position to said second position, and hence said latch moves from said first latch position to said second latch position, said flexible brake band is moved from a position free of said rotation transmitting means to a frictional braking relationship with said rotation transmitting means; and d) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said latch to said first latch position when said sensing arm means is in said first position, and for yieldably urging said latch to said second latch position when said sensing arm means is in said second position.
a) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, said protrusion including a first groove, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
b) a latch mounted on said housing means, said latch rotatable about an axis of rotation, said latch having a first pin and a second pin mounted thereon, said first pin being in engagement with said first groove, said latch being arranged to move from a first latch position to a second latch position when said sensing arm means is moved from said first position to said second position;
c) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said second pin in a manner such that when said sensing arm means moves from said first position to said second position, and hence said latch moves from said first latch position to said second latch position, said flexible brake band is moved from a position free of said rotation transmitting means to a frictional braking relationship with said rotation transmitting means; and d) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said latch to said first latch position when said sensing arm means is in said first position, and for yieldably urging said latch to said second latch position when said sensing arm means is in said second position.
12. The chain saw of Claim 11, wherein said second end of said biasing means is connected to said latch on the same side of said axis of rotation of said latch as said second pin when said sensing arm means is in said first position, and on the opposite side of said axis of rotation when said cam is in said second position.
13. The chain saw of Claim 11, wherein said latch includes a second groove engageable with said biasing means and said second end of said biasing means is connected to said latch by engagement said second groove.
14. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless movement, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, and safety braking means for stopping said cutting chain, said safety braking means com-prising:
a) acceleration sensing means, mounted on said housing means, and having a cam, for sensing the acceleration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value;
b) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, said protrusion including a first groove, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
c) a latch mounted on said housing means, said latch rotatable about an axis of rotation, said latch having a first pin and a second pin mounted thereon, said first pin being in engagement with said first groove, said latch fur-ther having a lever arm adapted to disengagingly contact said cam, said latch being arranged to move from a first latch position wherein said lever arm is in contact with said cam to a second latch position wherein said lever arm is disen-gaged from said cam when said cam is moved from said first cam position to said second cam position and said sensing arm means is moved from said first position to said second position;
d) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said second pin in a manner such that when said latch moves from said first latch posi-tion to said second latch position said flexible brake band is moved from a position free of said rotation transmitting means to a frictional braking relationship with said trans-mitting means; and e) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldingly urging said latch to said first latch position when said sensing arm means is in said first position and said cam is in said first cam position, and for yieldingly urging said latch to said second latch position when said sensing arm means is in said second position and said cam is in said second cam position.
a) acceleration sensing means, mounted on said housing means, and having a cam, for sensing the acceleration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value;
b) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, said protrusion including a first groove, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
c) a latch mounted on said housing means, said latch rotatable about an axis of rotation, said latch having a first pin and a second pin mounted thereon, said first pin being in engagement with said first groove, said latch fur-ther having a lever arm adapted to disengagingly contact said cam, said latch being arranged to move from a first latch position wherein said lever arm is in contact with said cam to a second latch position wherein said lever arm is disen-gaged from said cam when said cam is moved from said first cam position to said second cam position and said sensing arm means is moved from said first position to said second position;
d) a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end connected to said second pin in a manner such that when said latch moves from said first latch posi-tion to said second latch position said flexible brake band is moved from a position free of said rotation transmitting means to a frictional braking relationship with said trans-mitting means; and e) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldingly urging said latch to said first latch position when said sensing arm means is in said first position and said cam is in said first cam position, and for yieldingly urging said latch to said second latch position when said sensing arm means is in said second position and said cam is in said second cam position.
15. The chain saw of Claim 14, wherein said second end of said biasing means is connected to said latch on the same side of said axis of rotation of said latch as said second pin when said latch is in said first latch position, and on the opposite side of said axis of rotation when said latch is in said second latch position.
16. The chain saw of Claim 14, wherein said latch includes a second groove engageable with said biasing means and said second end of said biasing means is connected to said latch by engagement with said second groove.
17. The chain saw of Claim 14, wherein said accele-ration sensing means having a cam comprises an arm pivotally attached to said housing means having a cam attached thereto and a weight member mounted on said arm.
18. The chain saw of Claim 17, wherein said weight member is movably mounted on said arm and further including fastening means for fixing said weight member in a predeter-mined position on said arm.
19. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless movement, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, and safety braking means for stopping said cutting chain, said safety braking means comprising:
a) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
b) acceleration sensing means, mounted on said housing means, and having a cam, for sensing the accel-eration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value;
c) a flexible band brake having a first end and a second end, said first end connected to said housing means and said second end connected to said protrusion in a manner such that when said sensing arm means moves from said first position to said second position said flexible band brake is moved from a position free of said rotation trans-mitting means to a frictional braking relationship with said rotation transmitting means;
19. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless movement, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, and safety braking means for stopping said cutting chain, said safety braking means comprising:
a) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, said sensing arm means having a protrusion mounted thereon, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first position to a second position;
b) acceleration sensing means, mounted on said housing means, and having a cam, for sensing the accel-eration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value;
c) a flexible band brake having a first end and a second end, said first end connected to said housing means and said second end connected to said protrusion in a manner such that when said sensing arm means moves from said first position to said second position said flexible band brake is moved from a position free of said rotation trans-mitting means to a frictional braking relationship with said rotation transmitting means;
Claim 19 continued,..
d) a latch mounted on said housing means, said latch rotatable about an axis of rotation and receiv-ingly engaging said protrusion of said sensing arm means, said latch further having a lever arm adapted to dis-engagingly contact said cam, said latch being arranged to move from a first latch position wherein said lever arm is in contact with said cam to a second latch position wherein said lever arm is disengaged from said cam when said cam is moved from said first cam position to said second cam posi-tion and said sensing arm means is moved from said first position to said second position; and e) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said sensing arm means to said first position when said sensing arm means is in said first position, and for yieldably urging said sensing arm means to said second position when said sensing arm means is in said second position.
d) a latch mounted on said housing means, said latch rotatable about an axis of rotation and receiv-ingly engaging said protrusion of said sensing arm means, said latch further having a lever arm adapted to dis-engagingly contact said cam, said latch being arranged to move from a first latch position wherein said lever arm is in contact with said cam to a second latch position wherein said lever arm is disengaged from said cam when said cam is moved from said first cam position to said second cam posi-tion and said sensing arm means is moved from said first position to said second position; and e) biasing means having a first end and a second end, said first end connected to said housing means and said second end connected to said latch, for yieldably urging said sensing arm means to said first position when said sensing arm means is in said first position, and for yieldably urging said sensing arm means to said second position when said sensing arm means is in said second position.
20. A chain saw as claimed in claim 19, wherein said second end of said biasing means is connected to said latch on the same side of said axis of rotation of said latch as said protrusion of said sensing arm means when said sensing arm means is in said first position, and on the opposite side of said axis of rotation when said sensing arm means is in said second position.
21. A chain saw as claimed in claim 20, wherein said protrusion comprises a pin on said sensing arm means and said latch includes a first groove receivable of said pin.
22. A chain saw as claimed in claim 21, wherein said second end of said flexible brake band is connected to said pin.
23. A chain saw as claimed in claim 22, wherein said latch includes a second groove engageable with said biasing means and said second end of said biasing means is connected to said latch by engagement with said second groove.
24. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless rotation thereabout, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, and safety braking means for stopping said cutting chain upon occurrence of kickback, said safety braking means comprising:
a pivotable sensing means pivotally attached to said housing means, for sensing kickback of said chain saw, said sensing means pivoting from a first position to a second position upon detection of kickback;
brake means, engageable of said rotation trans-mitting means, for preventing rotation transmission from Claim 24 continued...
said motor means to said cutting chain, said brake means movable from a position free of said rotation transmitting means to a position of frictional braking engagement with said rotation transmitting means to prevent rotation of said cutter chain;
a discrete pivotable member, pivotable about a pivot point from a first pivotable member position to a second pivotable member position;
biasing means having a first end and a second end, said first end engaging said housing means at a pre-determined location and said second end engaging said pivot-able member at a point removed from said pivot point, for yieldably urging said pivotable member to said first posit n when said pivotable member is in said first position and for yieldably urging said pivotable member to said secon position when said pivotable member is in said second position, an imaginary line connecting the point of enga e-ment of said biasing means with said housing means and t e point of engagement of said biasing means with said pivo able member lying on one side of said pivot point when said pivotable member is in said first pivotable member position and on the opposite side of said pivot point when said pivotable member is in said second pivotable member position;
said pivotable sensing means, said discrete pivotable member and said biasing means cooperating with said brake means to hold said brake means in a position
24. In a chain saw having housing means, manual gripping handle means mounted on said housing means, motor means carried by said housing means, a cutting chain, support bar means projecting forwardly from said housing means for supporting said cutting chain for endless rotation thereabout, rotation transmitting means drivingly connected to said motor means for driving said cutting chain, and safety braking means for stopping said cutting chain upon occurrence of kickback, said safety braking means comprising:
a pivotable sensing means pivotally attached to said housing means, for sensing kickback of said chain saw, said sensing means pivoting from a first position to a second position upon detection of kickback;
brake means, engageable of said rotation trans-mitting means, for preventing rotation transmission from Claim 24 continued...
said motor means to said cutting chain, said brake means movable from a position free of said rotation transmitting means to a position of frictional braking engagement with said rotation transmitting means to prevent rotation of said cutter chain;
a discrete pivotable member, pivotable about a pivot point from a first pivotable member position to a second pivotable member position;
biasing means having a first end and a second end, said first end engaging said housing means at a pre-determined location and said second end engaging said pivot-able member at a point removed from said pivot point, for yieldably urging said pivotable member to said first posit n when said pivotable member is in said first position and for yieldably urging said pivotable member to said secon position when said pivotable member is in said second position, an imaginary line connecting the point of enga e-ment of said biasing means with said housing means and t e point of engagement of said biasing means with said pivo able member lying on one side of said pivot point when said pivotable member is in said first pivotable member position and on the opposite side of said pivot point when said pivotable member is in said second pivotable member position;
said pivotable sensing means, said discrete pivotable member and said biasing means cooperating with said brake means to hold said brake means in a position
Claim 24 continued...
free of said rotation transmitting means during operation of the chain saw when said sensing means is in said first position and said pivotable member is in said first pivotable member position, and upon occurrence of kickback said sensing means cooperating with said pivotable member to move said pivotable member from said first pivotable member position to said second pivotable member position when said sensing means moves from said first position to said second position, said pivotable sensing means, said discrete pivotable member and said biasing means then cooperating with said brake means to hold said brake means in a position of frictional braking engagement with said rotation transmitting means to prevent rotation of said cutter chain.
free of said rotation transmitting means during operation of the chain saw when said sensing means is in said first position and said pivotable member is in said first pivotable member position, and upon occurrence of kickback said sensing means cooperating with said pivotable member to move said pivotable member from said first pivotable member position to said second pivotable member position when said sensing means moves from said first position to said second position, said pivotable sensing means, said discrete pivotable member and said biasing means then cooperating with said brake means to hold said brake means in a position of frictional braking engagement with said rotation transmitting means to prevent rotation of said cutter chain.
25. A chain saw as claimed in claim 24, wherein said pivotable sensing means comprises sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first sensing arm position to a second sensing arm position, said sensing arm means cooperating with said pivotable member to move said pivotable member from said first pivotable member position to said second pivotable member when said sensing arm means moves from said first sensing arm position to said second sensing arm position.
26. A chain saw as claimed in claim 24, wherein said pivotable sensing means comprises:
a) acceleration sensing means, pivotally mounted on said housing means, and having a cam, for sensing the acceleration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value,and b) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first sensing arm position to a second sensing arm position when an operator's limb approaches said cutting chain, said sensing arm means cooperating with said pivot-able member to move said pivotable member from said first pivotable member position to said second pivotable member position when said sensing arm means moves from said first sensing arm position to said second sensing arm position;
and said pivotable member has a surface adapted to disengagingly contact said cam, said pivotable member being arranged to move from said first pivotable member position wherein said surface is in contact with said cam to a second pivotable member position wherein said surface is disengaged from said cam when said cam is moved from said first cam position to said second cam position.
a) acceleration sensing means, pivotally mounted on said housing means, and having a cam, for sensing the acceleration of said chain saw, and for moving said cam from a first cam position to a second cam position when said acceleration rises above a predetermined value,and b) sensing arm means, pivotally mounted on said housing means, for sensing the approach of an operator's limb to said cutting chain, a portion of said sensing arm means being located in front of said gripping handle means during operation of said chain saw and arranged to be moved from a first sensing arm position to a second sensing arm position when an operator's limb approaches said cutting chain, said sensing arm means cooperating with said pivot-able member to move said pivotable member from said first pivotable member position to said second pivotable member position when said sensing arm means moves from said first sensing arm position to said second sensing arm position;
and said pivotable member has a surface adapted to disengagingly contact said cam, said pivotable member being arranged to move from said first pivotable member position wherein said surface is in contact with said cam to a second pivotable member position wherein said surface is disengaged from said cam when said cam is moved from said first cam position to said second cam position.
27. A chain saw as claimed in claim 25, wherein said acceleration sensing means having a cam comprises an arm pivotally attached to said housing means having a cam attached thereto and a weight member mounted on said arm.
28. A chain saw as claimed in claim 26, wherein said weight member is movably mounted on said arm and further including fastening means for fixing said weight member in a predetermined position on said arm.
29. A chain saw as claimed in claim 24, wherein said brake means comprises a flexible brake band having a first end and a second end, said first end connected to said housing means and said second end movable from a first brake end position wherein said flexible brake band is in a position free of said rotation transmitting means to a second brake end position wherein said flexible brake band is in a position of frictional braking engagement with said rotation transmitting means.
30. A chain saw as claimed in claim 28, wherein said second end is connected to said sensing means.
31. A chain saw as claimed in claim 28, wherein said second end is connected to said pivotable member.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US37681082A | 1982-05-10 | 1982-05-10 | |
| US376,810 | 1982-05-10 | ||
| US45790983A | 1983-01-14 | 1983-01-14 | |
| US457,909 | 1983-01-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1184476A true CA1184476A (en) | 1985-03-26 |
Family
ID=27007573
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000427836A Expired CA1184476A (en) | 1982-05-10 | 1983-05-10 | Chain saw braking system |
Country Status (6)
| Country | Link |
|---|---|
| CA (1) | CA1184476A (en) |
| DE (1) | DE3316899C2 (en) |
| FI (1) | FI81987C (en) |
| FR (1) | FR2526359B1 (en) |
| IT (1) | IT1163314B (en) |
| SE (1) | SE459240B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3802740A1 (en) * | 1988-01-30 | 1989-08-03 | Hilti Ag | MOTORIZED HAND DEVICE |
| DE4120875C2 (en) * | 1991-06-21 | 2000-06-08 | Stihl Maschf Andreas | Motor chain saw with brake device integrated in the sprocket cover |
| DE10353013A1 (en) * | 2003-11-13 | 2005-06-16 | Robert Bosch Gmbh | Hand tool |
| PL2447022T3 (en) | 2010-10-29 | 2013-08-30 | Spitznas Maschf Gmbh | Chain brake device for a chain saw operated by pressurised air |
| ITTO20111167A1 (en) * | 2011-12-16 | 2013-06-17 | Active Srl | BRAKING DEVICE FOR THE CUTTING CHAIN OF A MOTORIZED CHAIN CUTTING TOOL, IN PARTICULAR OF A CHAINSAW. |
| CN110449659B (en) * | 2019-07-22 | 2024-05-07 | 浙江亚特电器股份有限公司 | Oil pump position adjustment structure and chain saw of chain saw |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1389645A (en) * | 1964-01-08 | 1965-02-19 | Liogier Ets | Further training in door closers |
| US3934345A (en) * | 1974-10-15 | 1976-01-27 | Mcculloch Corporation | Snap-acting over-center chain saw safety brake and method of operation thereof |
| US4059895A (en) * | 1974-10-15 | 1977-11-29 | Mcculloch Corporation | Full position safety brake for portable chain saw |
| US3982616A (en) * | 1975-07-25 | 1976-09-28 | Textron, Inc. | Latch operated centrifugally released safety clutch for saws |
| DE7526726U (en) * | 1975-08-23 | 1975-12-11 | Stihl A Maschinenfabrik | Device for braking a motor-driven hand saw, in particular a chain saw |
| DE2602247C2 (en) * | 1976-01-22 | 1992-04-23 | Fa. Andreas Stihl, 7050 Waiblingen | Braking device on a motor-driven hand saw, in particular a motor chain saw |
| CA1059011A (en) * | 1976-04-19 | 1979-07-24 | Sidney Hirschkoff | Full position safety brake for portable chain saw |
| DE3027221A1 (en) * | 1980-07-18 | 1982-02-18 | Dolmar Maschinen-Fabrik Gmbh & Co, 2000 Hamburg | BRAKE DEVICE FOR BRAKING THE SAW CHAIN OF A PORTABLE MOTOR CHAIN SAW |
-
1983
- 1983-04-15 SE SE8302101A patent/SE459240B/en not_active IP Right Cessation
- 1983-05-06 FR FR8307634A patent/FR2526359B1/en not_active Expired
- 1983-05-06 IT IT20963/83A patent/IT1163314B/en active
- 1983-05-06 FI FI831573A patent/FI81987C/en not_active IP Right Cessation
- 1983-05-09 DE DE3316899A patent/DE3316899C2/en not_active Expired - Fee Related
- 1983-05-10 CA CA000427836A patent/CA1184476A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FI831573L (en) | 1983-11-11 |
| IT8320963A1 (en) | 1984-11-06 |
| IT1163314B (en) | 1987-04-08 |
| FR2526359B1 (en) | 1986-09-12 |
| SE8302101L (en) | 1983-11-11 |
| IT8320963A0 (en) | 1983-05-06 |
| SE459240B (en) | 1989-06-19 |
| FI831573A0 (en) | 1983-05-06 |
| DE3316899A1 (en) | 1983-11-24 |
| FI81987B (en) | 1990-09-28 |
| FR2526359A1 (en) | 1983-11-10 |
| FI81987C (en) | 1991-01-10 |
| SE8302101D0 (en) | 1983-04-15 |
| DE3316899C2 (en) | 1994-09-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |